Despite the fact that I have a beetle blog and Alex has an ant blog, it is the latter where the regular series Friday Beetle Blogging resides (hmm, I wonder if I should start a Myrmecine Monday series?). Alex has perhaps the best science-based entomoblog out there, so I’m thrilled to contribute today’s edition – check it out: Friday Beetle Blogging – the Swift Tiger Beetle.
Copyright © Ted C. MacRae 2010
In the early 1980s, I was a young, green entomologist, fresh out of school with a budding interest in beetle taxonomy, a zeal for collecting, and a desire to meet other like-minded individuals. Among the first collectors I had the good fortune to meet was Ron Huber, one of the country’s leading tiger beetle experts and co-founder of the journal CICINDELA (now 42 years as co-editor). Although my interests had by then already begun narrowing to woodboring beetles, I liked tiger beetles well enough and managed to secure from him a single specimen of what Erwin and Pearson (2008) would later dub the “Great Plains giant tiger beetle,” Amblycheila cylindriformis – the largest tiger beetle in North America. I don’t remember what prompted Ron to part with this spectacular specimen – perhaps it was the lone Proserpinus gaurae (Lepidoptera: Sphingidae) adult that I possessed, which I had reared from a field-collected larva around that time, or maybe Ron had such a nice series of the species that making the day of a young collector was in itself reward enough. While clearly a tiger beetle, it was still so different by virtue of its enormous size (the species ranges from 25-38 mm in length), somber coloration, small eyes, and strictly nocturnal habit. For much of the past 25 years, that specimen has sat in my cabinet amongst a small assortment of other, mostly mundane tiger beetles that I had opportunistically taken on my woodboring beetle-focused collecting trips. While I longed to someday see the species for myself, to do that would mean making a special trip out to the Great Plains – woodboring beetle desert that it is – during the middle of summer and stumbling through the prairie in the dark with a flashlight. Such an effort always seemed too great for the sole purpose of finding a single species, and not even a woodboring beetle at that.
Interests evolve, however, and while I still consider woodboring beetles to be my primary interest, tiger beetles have increasingly occupied my attention over the past several years. Contrary to woodboring beetles, the Great Plains are a mecca for tiger beetle diversity, and in recent years I’ve made a number of trips to Nebraska, Kansas, South Dakota, and Oklahoma specifically to look for them. Such was the case in June of last year when I went to the Glass Mountains in northwestern Oklahoma on a hunch and found Cylindera celeripes, Dromochorus pruinina, and a large tiger beetle larva that I just recently concluded must represent A. cylindriformis. I had been rearing the larva for a year by the time I figured out its identity, and when I did I sudden found myself facing a “perfect storm” – an upcoming holiday weekend, adults presumably in peak adult activity, and I knew exactly where to look for them. Impulsively, I decided to use my July 4th weekend to make the 525-mile drive from St. Louis to the Glass Mountains – this would give me 2 nights to look for them and still allow me to make it back to work on Tuesday morning. Anything else I could find during the day would be icing on the cake, but even if I found nothing, the chance to see A. cylindriformis in the wild seemed worth the gamble.
I made it to Joplin, Missouri near the Oklahoma border by midnight on Friday but awoke to threatening skies the next morning. The threat of rain became a promise as I drove further west, and by the time I arrived in Enid, Oklahoma – just 30 miles from the Glass Mountains – it was raining heavily. I stopped at a coffee shop to access Wi-Fi, and checking the radar showed a line of storms moving up through Texas and western Oklahoma into Kansas – sitting right over the Glass Mountains! The forecast gave no reason for optimism, with a 50% chance of thunderstorms through the weekend. Smartly, I had recorded the locality of the Huber-specimen – collected in northwestern Kansas – and checked the forecast for that area, but it was even worse (50% chance of thunderstorms through Sunday and 80% Sunday night). Clearly this was not good, but I had made the drive and was determined to make something happen. I decided the best thing to do would be to just continue driving west – however far that was – until I got past the storm system and see what was around – wherever that might be. I gassed up amidst a gusty, torrential downpour and headed west out of town. As I drove, the rain lightened up and eventually ceased. The roads were wet, but at least it wasn’t raining, and when I arrived at the Glass Mountains even the roads seemed to be drying. Winds were still strong, but the clouds had broken somewhat, allowing brief periods of sun to further dry things out, and what followed was a most fascinating day on top of one of the Glass Mountain mesas (highlights include C. celeripes, D. pruinina, Microstylus morosus, Trichodes sp. – look for these in future posts). As dusk approached I searched the grasslands below hoping to see a rattlesnake or two – I had seen a western pygmy rattlesnake here last year, and western diamondbacks are also in the area, but I saw none.
Of course, all this was really just passing time – waiting for nightfall and hoping the rain continued to hold off so I could begin searching the prairie down below for A. cylindriformis. It had sprinkled once or twice during the day, and I couldn’t tell if the darkening western sky was truly rain or the just the coming dusk. At 9pm, with darkness fast approaching, I set out with my headlamp and made a beeline for the native prairie habitat on the lower talus slopes where I had last year collected the larva and observed additional larval burrows that I took to be the same species. I must admit that the thought of walking alone through the prairie at night in western diamondback rattlesnake habitat made me more than a little nervous, and I kept just as much an eye out for them as I did the tiger beetles that I was looking for. As the night wore on, my hopes began to dim – I had searched for almost an hour and had covered most of the area where I had seen larval burrows last year. With no sign of the beetle, the negative thoughts started to enter my head – did I make this drive for nothing? How sure was I that the larva really represented Amblycheila? Did I have the right search image? I mean, they’re huge black beetles – they should be easy to spot, right? Oh great, I made all this fuss on my blog about looking for the species – how embarrassing to have to say, “Uhm, well, I didn’t find it.” Just as I began wrapping back around the bottom of the talus slope, there it was – no doubt about it! I just watched it for a while and noted that it moved with some urgency, but it was not the speedy, jerking walk of ‘regular’ tiger beetles – rather, it was more lumbering, seeming to pick each foot up rather high, like a cat with rubber bands on its feet (how would I know about that?). There seemed little risk of it escaping me, so I got out the camera and began following it to take photographs – no way! While it may have lacked the speed of other tiger beetles, it also lacked their propensity to occasionally pause long enough to allow a shot or two. Add the darkness, fear of rattlesnakes, and constant bumping of the flash unit on my headlamp, and it was soon apparent that getting good field photographs was going to be a low percentage proposition. I resigned myself to taking photographs later in a terrarium (several shown here) and spend my time in the field more productively looking for additional individuals.
Finding the first individual did wonders for my motivation, and though still nervous about the potential for rattlesnakes I continued searching an ever-widening swath of the talus slope and adjacent areas. Another hour passed, and I had searched not only the native prairie below the talus slopes, but clay exposures on adjacent somewhat altered habitat. Again, the negative thoughts started creeping back into my mind – am I really gonna walk away from here with a single individual? I can say I found it, but that was a long drive for one beetle! I continued searching along an adjacent drainage ditch, and by 11:30pm I conceded that my victory was small and walked back to the truck to get a container to fill with native soil for a terrarium. Though it was a bit of a walk back up to the talus slope where I had seen the larval burrows, I wanted to take soil from that area specifically to give myself the best shot at obtaining eggs from my single (hopefully female) individual for an attempt at rearing more specimens from larvae. As I approached the exact spot where I had collected last year’s larva, I saw another, even larger adult! I don’t know which was greater – my excitement at finding such a large individual, or my relief in knowing that I would not go home with only one. Of course, with the second individual came a new shot of motivation, so once again I scanned across the talus slopes, and during the next half hour I found two more very near to where I had found the second one. By then it was past midnight, so I set about the business of digging soil for the terrarium. I finished the job (getting stung something terrible by three red, big-headed ants that had crawled up my pant leg while I was digging), took one last sweep across the immediate area, and turned to walk back to the truck when I saw the biggest one of all – I later determined it to be a male measuring 35 mm in length (that’s just about an inch and a half, folks!). With five individuals now, the urgency to find more was gone, and I decided I’d done what I needed to do and should get into town and find a hotel room. As I walked back to the truck, rain began to fall – lightly at first but ever increasing. Once back at the truck it was raining persistently enough that I could only hurriedly take some quick photographs of the beetles in their terrarium as in situ documentation of the momentous occasion!
Occurrence of Amblycheila cylindriformis. White arrows indicate where adults were found, all of which were on red clay/gypsum exposures on lower talus slopes in native prairie habitat. No adults were seen in clay/gypsum exposures further below the slopes in either native (zone 1) or altered prairie (zone 2) or further down in roadside drainages (zone 3).
Although I had accomplished my main goal, I looked forward to the opportunity the next day to search for C. celeripes at other nearby sites to better understand the extent of the area’s population. Sadly, the rain that had held off for nine hours before returning just after midnight was back for good, with radar the next morning showing a broad swath of rain extending across the entire western part of Oklahoma and north into Kansas. There wasn’t much for me to do but savor the previous day’s experience while I made the 525-mile drive back east. This may represent a significant record for the species – Vaurie (1955) in her review of the genus did not see any specimens from Oklahoma (although she did examine a few specimens from adjacent areas of Kansas), and Drew and Van Cleave (1962) reported only a single specimen from the state in nearby Woodward County. Significant record or not, it was an experience that I’ll not soon forget.
Photo Details: Canon 50D (ISO 100, 1/250 sec), Canon MT-24EX flash.
Photos 1-3: Canon 100mm macro lens (f/14-20), flash 1/4 power w/ Sto-Fen diffusers.
Photo 4: Canon MP-E 65mm 1-5X macro lens (f/14), flash 1/8 power w/ Sto-Fen + Gary Fong Puffer diffusers.
Post-processing: levels, unsharp mask, slight cropping on photo 1.
Note to self: clean specimens with moist brush to remove dirt before photographing them!
REFERENCES:
Drew, W. A. and H. W. Van Cleave. 1962. The tiger beetles of Oklahoma (Cicindelidae). Proceedings of the Oklahoma Academy of Science 42:101–122.
Erwin, T. L. and D. L. Pearson. 2008. A Treatise on the Western Hemisphere Caraboidea (Coleoptera). Their classification, distributions, and ways of life. Volume II (Carabidae-Nebriiformes 2-Cicindelitae). Pensoft Series Faunistica 84. Pensoft Publishers, Sofia, 400 pp.
Vaurie, P. 1955. A review of the North American genus Amblycheila (Coleoptera, Cicindelidae). American Museum Novitates 1724:1–26.
Copyright © Ted C. MacRae 2010
I love it when a plan comes together!
Another one was caught after these photos for a total of five individuals. They’ve been setup for now in a container of native soil. I hope you’ll forgive these rather rushed photos – they were hurriedly taken at half past midnight with rain beginning to fall. Details and much better photographs will, of course, be forthcoming.
I don’t think I have ever worked as hard for five specimens as I did tonight!
Copyright © Ted C. MacRae 2010
Glass Mountains, Oklahoma
Since figuring out a couple weeks that I had the larva of North America’s largest tiger beetle (Amblycheila cylindriformis, or Great Plains giant tiger beetle) in a rearing tub in the lab, I haven’t been able to think about anything except how cool it would be to go back out to the Glass Mountains in northwest Oklahoma (where I collected the larva last June) and look for the adults. I have every reason not to do this trip – I just spent a long weekend up in northwest Missouri on follow up surveys for our newly discovered population of Cylindera celeripes (swift tiger beetle) (my second such trip in the past three weeks¹), and in a mere week and a half I leave for a 2-week trip to France. Bills need to be paid, the grass needs cutting, and (as of today) a broken spoke needs to be repaired. My collecting trips are normally planned far in advance – their timing and frequency part of a delicate balance between the goals I set for the season and the responsibilities that go along with having a job and a family.
¹ More on this in an upcoming post.
But for Amblycheila, it’s now or never – at least for this season, and the thought of waiting until next year before I can take my first valid shot at finding this species in the wild (and perhaps a previously unrecorded population, at that²) is just too unbearable. So here I am, halfway to the Glass Mountains on as impulsive a trip as I’ve taken in a long time, hoping that my hunch pays off and I’ll find the strikingly large adults of A. cylindriformis lumbering below the flat-topped mesas in the mixed grass prairie where a little more than a year ago I was collecting its enormous larva. It’s a drive-collect-drive trip, and if successful I won’t be the first person to photograph them, even well, but it will nevertheless fulfill my longtime desire to locate this species in the wild and see it with my own eyes – a far more gratifying experience than looking at the lone dead specimen acquired long ago through trade that sits in my cabinet. Wish me luck!
² Drew and Van Cleave (1962) saw only a single specimen from the state in neighboring Woodward Co., although this is now a rather old reference.
REFERENCES:
Drew, W. A. and H. W. Van Cleave. 1962. The tiger beetles of Oklahoma (Cicindelidae). Proceedings of the Oklahoma Academy of Science 42:101–122.
Copyright © Ted C. MacRae 2010
Typocerus lugubris on Hydrangea arborescens, Trail of Tears State Park, Missouri.
Members of the genus Typocerus are among the more commonly encountered species of the so-called “flower longhorns” (family Cerambycidae, subfamily Lepturinae) in eastern North America. In addition to the narrow-necked, broad-shouldered appearance characteristic for the subfamily, species in this genus are recognizable by their strongly tapering elytra, strongly basally depressed prothorax, and apically produced antennal segments with distinct poriferous areas (Linsley and Chemsak 1976).
Eight of the 15 species known from North America occur in Missouri, where they are commonly encountered on a variety of flowers during the months of June and July. Some of these species can be difficult to distinguish from each other – in fact, Missouri’s rarest species (Typocerus deceptus) is almost identical in appearance to one of Missouri’s commonest species (Typocerus velutinus), and several other species resemble them closely enough to require careful attention details of coloration when attempting identification.
Typocerus lugubris is not one of those species, its all-black coloration making it quite distinctive within the genus. Two other species in Missouri are mostly black, but unlike T. lugubris they always bear yellow blotches in the basal area of the elytra (T. lunulatus) or exhibit yellow transverse bands (T. zebra). Typocerus confluens also is a rather uncommon species in Missouri that varies from chestnut brown to nearly all black, but it is much more robust than T. lugubris (and also bears erect hairs on the pronotum and lacks poriferous areas on antennomere 6). The remaining species tend to be chestnut colored, at least in the basal area of the elytra, with more or less distinct transverse yellow banding.
Photo Details: Canon 50D (ISO 100, 1/250 sec, f/18), Canon 100mm macro lens, Canon MT-24EX flash (1/4 ratio) w/ Sto-Fen diffusers. Post-processing: levels, minimal crop, unsharp mask.
REFERENCES:
Linsley, E. G. and J. A. Chemsak. 1976. The Cerambycidae of North America. Part VI, No. 2. Taxonomy and classification of the subfamily Lepturinae. University of California Publications in Entomology 80:ix + 1–186.
Copyright © Ted C. MacRae 2010
I’m particularly enamored with glades, and after nearly 30 years of exploring Missouri’s Ozark Highlands, there aren’t many glades of any significance that I haven’t visited at some time or another. However, during my mostly unproductive Memorial Day weekend collecting trip, I had a chance to visit Bona Glade Natural Area in Dade County for the first time. Located in southwestern Missouri where the Ozark woodlands of the Springfield Plateau begin transitioning to the grasslands of the Great Plains, this small (20 acres) sandstone glade is noted as a station for the federally threatened and state endangered Geocarpon minimum. I did not see this diminutive plant (sometimes called tinytim) during my visit, but I did see another pretty little succulent – Sedum pulchellum. Also called widowscross, this plant belongs to the Crassulaceae – the same family as the familiar jade houseplant.
Although not nearly as rare as Geocarpon, widowscross is nevertheless somewhat restricted in Missouri, occurring primarily in the southwestern quarter of the state. Throughout much of its range it is primarily associated with calcareous limestone glades, ledges, and outcrops (Baskin and Baskin 1977), but in Missouri it grows also on acidic chert and sandstone glades (Yatskievych 2006) – as is the case at Bone Glade. I’ve not encountered this plant before, thus when I spotted this little stand with its profusion of brilliant pink blossoms, it immediately caught my attention. A winter annual, this species prefers full sun and well drained, disturbed soils and apparently produces seeds quite prolifically when grown under the right conditions. These features, along with its petite attractiveness, would seem to make it an ideal native alternative for succulent gardens.
Another, much less common sedum also occurs at Bona Glade, Sedum nuttallianum (Nuttall’s sedum). This species is similar to S. pulchellum but can be distinguished by its smaller leaves and yellow blossoms. It’s range is similar to that of Geocarpon, growing almost exclusively on chert and sandstone glades from southwestern Missouri and southeastern Kansas south to Louisiana and Texas. I did not see this plant either – in fact, after finding this small stand of S. pulchellum I searched the entire glade rather thoroughly and did not see any other plants of that species either.
Photo Details: Canon 50D (ISO 100-200, 1/400-500 sec, f/5.6), Canon 100mm macro lens, ambient light. Post-processing: minor cropping, levels, unsharp mask.
REFERENCES:
Baskin, J. M. and C. M. Baskin. 1977. Germination ecology of Sedum pulchellum Michx. (Crassulaceae). American Journal of Botany 64(10):1242-1247.
Yatskievych, G. 2006. Steyermark’s Flora of Missouri, Volume 2. The Missouri Botanical Garden Press, St. Louis, 1181 pp.
Copyright © Ted C. MacRae 2010
I’ve mentioned before the considerable taxonomic challenges facing students of the family Buprestidae (jewel beetles) in North America, owing largely to fact that more than half of its species are assigned to one of just three hyper-diverse genera (Acmaeodera, Agrilus, and Chrysobothris). New species continue to be described, but the most recent comprehensive treatments of these three genera were published more than 60 to 100 years ago (Fall 1899, Fisher 1928, Fisher 1945)! The situation is not as dire in the “other” major woodboring beetle family – the Cerambycidae (longhorned beetles), thanks in great part to the efforts of Gorton Linsley and John Chemsak and their monographic series of the family’s North American species (Linsley 1961-1964, Linsely and Chemsak 1972-1997). Although somewhat more speciose in North American than the Buprestidae, diversity in the Cerambycidae is more apparent at the generic level (1000+ species in 325 genera, compared to 787 species in only 54 buprestid genera). This does not mean, however, that the Cerambycidae lacks problematic, speciose genera, and in a recently published paper, Ian Swift and Ann Ray (2010) tackle one of these – the genus Phymatodes. While no new species are described, their treatment does propose numerous nomenclatural changes based on examination of type specimens that affect several North American species, including correcting misapplied names and recognizing multiple synonymies. These problems resulted from the practice of many earlier authors who did not examine type specimens when describing new species, relying instead only on written descriptions to compare taxa.
While this paper is not a full revision of the genus, it does include diagnostic and comparative notes, full color dorsal habitus photographs (example plate below), and an updated key to all of the species found in North America.
PLATE 1. 1) Phymatodes aeneus, male; 2) P. aereus, female; 3) P. amoenus, female; 4) P. amoenus, female ventral; 5) P. ater, female; 6) P. ater, female; 7) P. blandus, male; 8 ) P. concolor, male; 9) P. decussatus, male. © Swift & Ray 2010.
The genus Phymatodes is most diverse in the western states and provinces – I haven’t spent as much time out there as in other areas of North America, so representation of this genus in my collection is rather weak at only 10 of the 26 species currently recognized in North America. Missing from my cabinet are the following – if anyone is able to help me out with these I would be most grateful:
REFERENCES:
Fall, H. C. 1899. Synonpsis of the species of Acmaeodera of America, north of Mexico. Journal of the New York Entomological Society 7(1):1–37 [scroll to “Journal of the New York Entomological Society”, “v. 7 1899”, “Seq 12”].
Fisher, W. S. 1928. A revision of the North American species of buprestid beetles belonging to the genus Agrilus. U. S. National Museum 145, 347 pp.
Fisher, W. S. 1942. A revision of North American species of buprestid beetles belonging to the tribe Chrysobothrini. U. S. Department of Agriculture, Miscellaneous Publication 470, 275 pp.
Linsley, E. G. 1961. The Cerambycidae of North America. Part I. Introduction. University of California Publications in Entomology 18:1–97.
Linsley, E. G. 1962. The Cerambycidae of North America. Part II. Taxonomy and classification of the Parandrinae, Prioninae, Spondylinae and Aseminae. University of California Publications in Entomology 19:1–102.
Linsley, E. G. 1962. The Cerambycidae of North America. Part III. Taxonomy and classification of the subfamily Cerambycinae, tribes Opsimini through Megaderini. University of California Publications in Entomology 20:1–188.
Linsley, E. G. 1963. The Cerambycidae of North America. Part IV. Taxonomy and classification of the subfamily Cerambycinae, tribes Elaphidionini through Rhinotragini. University of California Publications in Entomology 21:1–165.
Linsley, E. G. 1964. The Cerambycidae of North America. Part V. Taxonomy and classification of the subfamily Cerambycinae, tribes Callichromini through Ancylocerini. University of California Publications in Entomology 22:1–197.
Linsley, E. G. and J. A. Chemsak. 1972. The Cerambycidae of North America. Part VI, No. 1. Taxonomy and classification of the subfamily Lepturinae. University of California Publications in Entomology 69:viii + 1–138.
Linsley, E. G. and J. A. Chemsak. 1976. The Cerambycidae of North America. Part VI, No. 2. Taxonomy and classification of the subfamily Lepturinae. University of California Publications in Entomology 80:ix + 1–186.
Linsley, E. G. and J. A. Chemsak. 1984. The Cerambycidae of North America, Part VII, No. 1: taxonomy and classification of the subfamily Lamiinae, tribes Parmenini through Acanthoderini. University of California Publications in Entomology 102:ix + 1–258.
Linsley, E. G. and J. A. Chemsak. 1995. The Cerambycidae of North America, Part VII, No. 2: taxonomy and classification of the subfamily Lamiinae, tribes Acanthocinini through Hemilophini. University of California Publications in Entomology 114:xi + 1–292.
Linsley, E. G. and J. A. Chemsak. 1997. The Cerambycidae of North America, Part VIII: bibliography, index, and host plant index. University of California Publications in Entomology 117:ix + 1–534..
Swift, I. P. & A. M. Ray. 2010. Nomenclatural changes in North American Phymatodes Mulsant (Coleoptera: Cerambycidae). Zootaxa 2448:35–52.
Copyright © Ted C. MacRae 2010
The generous among us might call it serendipity, while the rest of us would just call it luck. By whatever name, I had it in spades in June last year when I made my first visit to the Glass Mountains of northwestern Oklahoma. My original plan was to go to Tallgrass Prairie Preserve in eastern Oklahoma at the end of what proved to be a resoundingly successful day at Alabaster Caverns State Park. However, soaking rains moved into the area and continued rumbling eastward across the plains towards the preserve, forcing a quick change of itinerary. I decided to wait it out in the state’s western reaches, a “hunch” telling me that the red clay/gypsum hills in nearby Major County might be a fruitful place for hunting tiger beetles. Sunny skies the next morning were a good sign, and my hunch was rewarded later that day when I discovered a previously unknown (and fortunately robust) population of the rare Cylindera celeripes (swift tiger beetle), making not just the day but the entire trip more successful than I could have ever imagined. Icing on the cake came when I found decent numbers of the more secure but nevertheless uncommon Dromochorus pruinina (frosted dromo tiger beetle) also in the area.
Another find I made that day that I’ve mentioned on occasion but not talked about at length was a single, rather large tiger beetle larva. I found several burrows at the base of a talus slope at the edge of a small ravine where many adult C. celeripes were scurrying, and though I tried with many, out of only one did I manage to “fish” its occupant with a blade of grass. I didn’t know which species it represented, but its large size and occurrence in clay soil brought to mind two species – Cicindela pulchra (beautiful tiger beetle) and C. obsoleta (large grassland tiger beetle). Both of these Great Plains species reach their eastern limit of distribution in this part of Oklahoma (Pearson et al. 2006), and their status as the largest species of the genus (and its former subgenera) in North America seemed to make them the leading candidates for this enormous larva. There was one other possibility – Amblycheila cylindriformis (Great Plains giant tiger beetle), another Great Plains species at its eastern limit in western Oklahoma and (as the common name implies) the largest tiger beetle in all of North America. However, to consider that species seemed too much wishful thinking. From my understanding, larvae of that elusive species reach an incredible 45 mm in length and dig burrows on steep slopes or at the mouths of rodent burrows that extend vertically to depths of up to 1.5 m or more (Brust et al. 2005). Surely I could not have so casually stumbled upon such a grand grub!
I placed the larva in a terrarium of native soil and brought it back with me, and for one year now I have waited – feeding it a regular diet of the fat noctuid caterpillars that we rear so abundantly in our lab. For a full year, I’ve watched it nab caterpillar after caterpillar, disappearing mysteriously for days on end, and just as mysteriously reappearing at the top of its burrow. I knew getting a closer look at it would help in my attempts to determine its identity, but every time I approached with a camera it dodged down into its burrow and beat my patience. Sometimes I would see it sitting about a centimeter below the burrow entrance – just waiting for a caterpillar to crawl by but refusing to expose itself to the lens. I gradually decided it was likely C. pulchra, as I had seen that species in similar habitat not too far north in Barber County, Kansas. So strong was my suspicion that I even made another trip out to the Glass Mountains in October of last year, expecting to see the fall-active adults bejeweling the exposed flats below the red clay slopes, their wine-red elytra and purple-margined bodies all aglitter under the crisp, autumn sun. No such sight was beheld, however – my hopes dashed by the season’s sudden cold and wet turn, and with the terrarium containing the larva by then tucked away in a cool incubator for a winter’s rest, it would be several months before I would see the larva once again sitting at the top of its burrow.
In late March I pulled the terrarium out of the incubator, and within a week the larva reopened its burrow. I fed it a few times, and then one day I saw that it had dug a new, larger burrow – measuring a full 10 mm in diameter! This seemed extraordinarily large for any species of Cicindela, so I resolved once again to photograph it and determine its identity. For days I stalked it, keeping the terrarium just outside my office door where I could keep an eye on it, yet every time I approached within two feet or so it would drop down out of sight. I decided to stop feeding it – perhaps hunger would overwhelm its patience and prompt it to return to the top of its burrow more quickly after retreating. That seemed to work, as one day the larva came back up after only a few minutes – and I was ready! Already in position, I flashed off multiple shots as soon as it reappeared, moving slowly and deliberately between shots to avoid spooking it again, and managed to get a nice series from varying distances. As a testament to its enormous size, all of the photos shown here were taken with the standard 100mm macro lens (1X maximum) – not the 65mm 1-5X beast that I needed for these shots of the super-tiny C. celeripes.
Thinking that the larva likely represented C. pulchra, I compared the photos to this photo taken by Matt Brust of a 3rd-instar larva of C. pulchra and immediately noted the differently shaped pronotum of my larva and its distinctly projecting anterolateral angles. Compare to C. pulchra, in which the angles are in line with the median part of the anterior margin – it is clearly not that species. It isn’t C. obsoleta either, as that species has the anterolateral angles of the pronotum even less projecting than C. pulchra (Drew and Van Cleave 1962). Apparently I needed to rethink my assumption that it belonged to Cicindela or its close relatives – none that occur in Oklahoma are simply large enough! Tetracha virginica is large enough, but I knew it wasn’t that species since it lacked the white margined pronotum distinctive of species in that genus (as can be seen in this post on the larva of Tetracha florida). That left only A. cylindriformis, distinguishable from all other tiger beetle genera occurring in Oklahoma by the second (lower) pair of eyes distinctly smaller than the first (Hamilton 1925, Drew and Van Cleave 1962, Pearson et al. 2006) – clearly seen in the third photo above. Matt Brust has also photographed the larva of A. cylindriformis – it’s not a close shot of the head and pronotum, but in general aspect my larva seems to match it well enough.
All that is left is to actually succeed in rearing this larva to adulthood. These beasts may require up to three to four years to develop (Brust et al. 2005), although this is likely influenced by latitude and prey abundance. I suspect it was a second instar larva when I collected it, and that it dug its new burrow this spring after molting to the third (and final) instar. Hopefully by keeping it in a nice, warm growth chamber and feeding it generously with fat caterpillars, I can minimize the time to pupation and perhaps see the adult sometime later this summer. If/when that happens, you can be sure to see a follow up to this post.
Photo Details: Canon 50D (ISO 100, 1/250 sec, f/16-18), Canon 100mm macro lens, Canon MT-24EX flash (1/4 ratio) w/ Sto-Fen diffusers. Post-processing: contrast and unsharp mask (no cropping).
REFERENCES:
Brust, M. L., S. M. Spomer and W. W. Hoback. 2005. Tiger Beetles of Nebraska. University of Nebraska at Kearney. http://www.unk.edu (Version 5APR2005).
Drew, W. A. and H. W. Van Cleave. 1962. The tiger beetles of Oklahoma (Cicindelidae). Proceedings of the Oklahoma Academy of Science 42:101–122.
Hamilton, C. C. 1925. Studies on the morphology, taxonomy, and ecology of the larvae of Holarctic tiger beetles (family Cicindelidae). Proceedings of the U.S. National Museum 65 (Art. 17):1–87.
Pearson, D. L., C. B. Knisley and C. J. Kazilek. 2006. A Field Guide to the Tiger Beetles of the United States and Canada. Oxford University Press, New York, 227 pp.
Copyright © Ted C. MacRae 2010
Beetles In The Bush 